[Vic-nyc]

Short summary of the article. The outage was caused by the introduction of new requirements by LSE for end-of-day price reporting. The data vendors were the ones who had the responsibility to adhere to these new rules, by making changes to their systems. Unfortunately, the "big bang" approach to the switch-over proved fatal.

From the article:

“I am astonished they did not run the systems in parallel,” said a source at one of the major data vendors. “At least for a few weeks or months as necessary.”

The LSE argues that it gave plenty of proper testing and preparation time, and that the vendors should have been ready. It has been working with them to resolve the issues.

[michaelcampbell]

> “I am astonished they did not run the systems in parallel,” said a source at one of the major data vendors. “At least for a few weeks or months as necessary.”

I worked at a wall street trading firm for some years in the past. Our group was primarily working on replacing older mainframe applications. After the normal back and forth with development and QA, they would be run in parallel with the systems they were replacing for a minimum of 3 months. Development was not allowed to install, monitor, "fix" or otherwise touch them during that time. We either got a "go" or "no go" periodically, and we had to fix whatever the issues were or they never saw the light of day.

[mithaler]

Why am I reminded of Douglas Adams? "All the planning charts have been on display at your local planning department in Alpha Centauri for 50 of your Earth years, so you've had plenty of time to lodge any formal complaint and it's far too late to start making a fuss about it now..."

[rbanffy]

I seriously doubt the plans were that far away. The transition was not announced the day before after all.

[andrew1]

I haven't followed the story that well, and only skim read this article, but there was a four-ish hour outage in the morning last week. I think the LSE came up OK for about half an hour but then went down (although it might not have come up at all; I can't remember). It seems unlikely that that was caused by data vendors not reporting end of day close prices correctly.